With the rapid development of modern industry, the production and variety of synthetic aromatic hydrocarbon compounds are increasing. These compounds are complex in structure and difficult to degrade naturally, exhibit carcinogenic or teratogenic activity to humans, can be transported over long distances in media such as the atmosphere, water, soil and organisms, causing widespread nonpoint source pollution and seriously threatening human health and ecological security. Thus, pollution control of aromatic hydrocarbon compounds is a major problem in ecological environmental protection.
Microorganisms are important drivers of material cycle and energy conversion in ecosystem, having the ability to degrade pollutants into non-toxic and harmless products. Using microorganisms to purify toxic and hazardous substances has been considered to be the most promising means of environmental pollution control at present. For a long period, scientists have carried out research on microbial degradation of organic pollutants from different angles. With the development and application of analysis and detection technology based on microbial physiology and ecology, a large number of studies have shown that, functional microorganisms that can degrade toxic aromatic hydrocarbon pollutants using their own enzyme systems are widely found in polluted environments. These microorganisms with degradation function play an irreplaceable role in the purification and recovery of polluted environment, and are an important force for accelerating the removal of aromatic hydrocarbon pollutants.
The isolation and selection of microorganisms capable of efficiently degrading aromatic hydrocarbon pollutants is the core task for the control and recovery of aromatic hydrocarbon-polluted environment and accelerating the removal of aromatic hydrocarbon pollutants. For a single cell obtained by the conventional plate isolation and screening techniques, its characteristics and function will be manifested only after this single clone proliferates to form a population, which results in delay and low sensitivity in function characterization. Meanwhile, the heterogeneity between microbial cells in a population will lead to uncertainty in the function characterization, which reduces the accuracy of screening. Moreover, the conventional screening methods are only applicable for selecting the functional microorganisms that grow faster in specific media, but inapplicable for the analysis and selection of microorganisms that are difficult to grow or grow slowly. Thus, rapid and accurate analysis and screening of microbial functional activity at single cell level is the key to efficient selection of functional microorganisms.
Compared with the traditional analysis and detection techniques for cell function and metabolic activity, such as enzyme activity detection and metabolite analysis, fluorescent labeling technique is a rapid and convenient biological analysis method. Fluorescence-activated cell sorting (flow cytometry) enables rapid, high-sensitivity analytical sorting of single cells. However, fluorescent probes used in bacteria screening studies are mostly generic nucleic acid probes, which is inapplicable for tracking the functional activity of microorganisms. Nanoscale fluorescent probes used for tracking microorganisms, as they exhibit high locating capability and the fluorescent substances will not be easily leaked, can solve the problem of non-specific tracking of microbial functional cells. Using fluorescence energy transfer technology to construct nanoscale fluorescent probes for target contaminants, which realizes rapid, accurate analysis and tracking of single functional cells, and in combination with FACS to establish a high-throughput screening method for efficient, intuitive, and specific tracking of functionally active strains, can significantly improve the efficiency of isolation and selection of functional microorganisms, not only providing important technical support for single-cell level studies of functional microorganisms and the deep excavation of undiscovered functional microbial resources, but also providing valuable bacteria resources for microbial treatment and recovery of environmental pollution.